Step one run the laser file through your machine. Once all parts are cut out:

1. Build the slider door, Take the small rectangle with the oval scored on its face and put a small drop of CA/Super glue in the center of the oval. Attach the small oval cutout centered in the scored oval.  (*If you prefer, you can use the slider that has the oval cut out and skip this step)
   1. Once attached, I recommend you wax/oil these pieces. I use a beeswax/mineral oil finish and it worked great. A waxy style finish will help the slider move easily.
2. Take the thinner walled rectangle frame (larger inside gap) and align it with the bottom corners of the backer unit. The words Mom and Dad should be centered in this frame if placed correctly. Glue in place and allow glue to set. 
3. Place the slider door inside the frame and make sure it moves freely. Once checked. Align the slider in the middle of the opening. 
4. Attach the top retaining rectangle frame (the thicker walled frame) and align bottom corners with bottom corners of the existing frame and base. Glue in place being careful not to glue the slider in the process. 
   1. Two options that worked for me
      1. Place slider in middle and only glue frame along edges where the slider would not contact the glue. This will leave the center edges unglued but this should not be an issue. 
      2. Place slider on one side of the space and glue the opposite side of the retainer. Once glue has set, move slider to opposite side and carefully insert glue on the remaining side being careful not to break the frame.